Stock Ecu reflash/reprogramming

[Hamapuka]

Can I swap stock 240sx ecu with same part number without refreshing or reprogramming? Any experience here is appreciated

[tunermt]

Yes that is fine. As long as the OEM ecu your are swapping out was not "rom tuned" then there should be no change as long as you are using the same part # ECU.
IF the original ECU was ever tuned/chipped then you would "loose" your tune when switching to a new to you oem ecu.

Good luck and hope you now have an easy solution to your problem
If not you may consider swapping out to a proper standalone SR20det ECU in which case it can be tuned to support any engine configuration/fuel you are running.